Electronic device having communication function

ABSTRACT

This invention concerns a network comprising a master and slaves. In the network, each slave figures out its performance values as performance parameters and transmits the performance parameters to the master. The master performs a process of selecting a backup master as a candidate for the next master, on the basis of the performance parameters transmitted from the slaves. The master supplies BM information containing synchronization information and the address of the backup master selected, to the slaves. When the master is removed from the network, the slaves determine the next master in accordance with the backup-master information. Thus, the slaves can be immediately connected to the next master.

TECHNICAL FIELD

The present invention relates to a communication processing apparatus, acommunication processing system and a communication processing method,and also to a computer program. More particularly, the invention relatesto a communication processing apparatus, a communication processingsystem, a communication processing method and a computer program whichcan easily and quickly switch a master device that functions as acommunication routing device or a control device for use in wirelesscommunication represented by, for example, Bluetooth®.

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2002-292333, filed Oct. 4, 2002, theentire contents of which are incorporated herein by reference.

BACKGROUND ART

Bluetooth has been attracting attention as means for achievingshort-distance wireless communication. Various devices compliant withBluetooth have been developed and on the market.

Systems for wireless communication by means of Bluetooth have nodirectivity and high transmissivity. They are therefore advantages overthe conventional infrared communication system such as IrDA (InfraredData Association). To use high-directivity communication by means of,for example, IrDA, the devices between which to accomplishedcommunication should be appropriately positioned to face each other.Such positioning is unnecessary in any communication system that employsBluetooth.

Bluetooth SIG Inc. controls the standards of Bluetooth. The details ofthe standards are available to any person. In any communicationutilizing Bluetooth, a device called “master” that controls thecommunication transmits, by broadcasting, a device detection message fordetecting the devices that exist around the master.

The master can detect any device (slave) that exists around it and hasreceived the device-detecting message, when it receives a responsemessage transmitted from the device that can communicate with it.

To establish communication with the device thus detected, the masteridentifies the device on the basis of the ID information that iscontained in the response message. The communication with this device isthereby established.

In Bluetooth, each device is assigned with ID information called“Bluetooth-device address,” which is used to identify the device. Sincethe ID information is unique to the device, it is utilized in variousprocesses such as the management of the device.

In Bluetooth, a network composed of a master and slaves is called“piconets.” In the piconet, up to seven slaves can belong to one master.All devices of the piconet are synchronized in terms of frequency axis(frequency hopping pattern) and time axis (time slot).

A plurality of piconets may be connected to one another, thusconstituting a larger network, which is called “scatter net.”

In Bluetooth, specification which is called “profile” is defined foreach service item, in connection with the data to be transmitted andreceived by wireless communication and the procedure of wirelesscommunication. The service that each device can provide is describedaccording to the profile.

PAN (Personal Area Network) profile describes the method ofcommunication between the slaves of a piconet. Any device of the piconetconfigured on the basis of the PAN profile can transmit and receivevarious data items in the piconet, which is one network. It is plannedthat, in a scatter net, too, any device can transmit and receive variousdata items because the scatter net is also a network. This network canbe a network based on IP (Internet Protocol).

In the process of constructing such a network, it is necessary todetermine which device should be the master, which device should be aslave, and which service should be used to achieve communication. It isthe master that determines these, by acquiring the information about thedevices existing around it, from the above-mentioned response message orthe like, and in accordance with the instructions of the user.

When the master is removed from the piconet, the slaves can no longercommunicate with one another through the master in the piconet. Thecommunication must be stopped, and it is necessary to set one of theslaves as master, thereby constructing a new piconet.

At present, one of the devices is not automatically set as master. Itneeds to be set as such manually by the user. Hence, the user isbothered to set a new master when the piconet ceases to exist due to theremoval of the master from the network, the power running-out of themaster battery, or the like. Unless the user set a slave as new master,no communication can be accomplished between the other slaves in thenetwork. The communication may be interrupted for a long time.

DISCLOSURE OF INVENTION

An object of the present invention is to provide a novel communicationprocessing apparatus, communication processing system and communicationprocessing method that can solve the problems of the prior art describedabove, and also to provide a computer program.

Another object of the invention is to provide a communication processingapparatus, a communication processing system and a communicationprocessing method, in which a new master can be set immediately afterthe master is removed from a piconet, thereby reducing to a minimum theinterruption of communication between the devices that constitute thepiconet, and also to provide a computer program.

Still another object of the present invention is to provide acommunication processing apparatus, a communication processing systemand a communication processing method, and also to provide a computerprogram. In the apparatus, system and method, the master evaluates aslave for its aptitude for use as master, on the basis of theperformance parameter supplied from the slave, selects the slave havingthe highest possibility, as next master, i.e., backup master, andtransmits the information of the backup master to every slave. Thus,when the master is removed from the piconet, the slaves can be connectedto the backup master immediately, thereby resuming the communication inthe piconet.

To attain the objects described above, a communication processingapparatus according to the present invention acts as a master in awireless communication network that comprises at least one slave whichcommunicates through the master. The apparatus is characterized byhaving: a data-receiving means for receiving data from each of theslaves that are devices constituting the wireless communication network,wherein capabilities of data processing for each item of evaluation areset as performance parameters in the data; a data-processing means forperforming a process of figuring out aptitude for a master based on theperformance parameters received from the slave and a process ofdetermining one slave as a backup master that is a candidate for nextmaster based on the aptitude; and a data-transmitting means fortransmitting backup-master information containing address informationand synchronization information, to each slave of the wirelesscommunication network, the address information corresponding to thebackup master determined by the data-processing means.

In the communication processing apparatus according to this invention,the performance parameters include at least one of data items ofremaining battery power, CPU performance, memory resource and RSSI,i.e., electric-field intensity, all pertaining to the slave, and thedata-processing means is configured to figure out the mater aptitudebased on at least one of the performance parameters.

In the communication processing apparatus according to the invention,the performance parameters may include at least one of data items ofremaining battery power, CPU performance, memory resource and RSSI,i.e., electric-field intensity, all pertaining to the slave, and thedata-processing means may be configured to figure out the mater aptitudeby performing an operation in which a weight coefficient is applied toat least one of the performance parameters.

In the communication processing apparatus according to the invention,the performance parameters may include a data item representing whetherthe slave can be a master, and the data-processing means may beconfigured to figure out the master aptitude only for the slave whosedata item represents to be a master.

In the communication processing apparatus according to this invention,the wireless communication network is a wireless communication networkthat performs Bluetooth communication, and the data-receiving means maybe configured to perform a process of receiving packets, each being aBNEP packet generated in accordance with Bluetooth network encapsulationprotocol (BNEP) and containing the performance parameters.

In communication processing apparatus according to the presentinvention, the wireless communication network is a wirelesscommunication network that performs Bluetooth communication, and thedata-transmitting means is configured to perform a process oftransmitting packets, each being a BNEP packet generated in accordancewith Bluetooth network encapsulation protocol (BNEP) and containing thebackup-master information.

In the communication processing apparatus according to this invention,the performance parameters are stored in a BNEP packet generated inaccordance with Bluetooth network encapsulation protocol (BNEP), and thedata-processing means may be configured to perform a process ofacquiring the performance parameters from the BNEP packets.

In the communication processing apparatus according to the invention,the data-processing means may be configured to perform a process ofstoring the backup-master information in a BNEP packet generated inaccordance with Bluetooth network encapsulation protocol (BNEP). Thebackup-master information includes address information corresponding tothe backup master and synchronization information.

In the communication processing apparatus according to the invention,the data-processing means further generates a backup-master activationrequest packet that requests for activation of the backup master, andthe data-transmitting means may be configured to perform a process oftransmitting the backup-master activation request packet to the backupmaster.

In the communication processing apparatus according to this invention,the data-processing means may be configured to perform a process ofstoring type information (Target UUID) in the backup-master activationrequest packet, the type information showing whether the master shouldbe set as a NAP (Network Access Point) or a GN (Group Ad-hoc Network).

In the communication processing apparatus according to the invention,the data-processing means may figure out master aptitudes for theslaves, based on the performance parameters received from the slaves,and generates a packet containing a list that contains the addressinformation items of the slaves and synchronization information, thelist showing the address information items in the order of the masteraptitudes of the respective slaves, and the data-transmitting means isconfigured to perform a process of transmitting the packet containingthe list, to the slaves constituting the wireless communication network.

In the communication processing apparatus according to the presentinvention, the data-processing means further generates a packet to betransmitted to the backup master, the packet containing a list thatcontains address information of the slaves that are devices constitutingthe wireless communication network and synchronization information, andthe data-transmitting means may be configured to perform a process oftransmitting the packet containing the list, to the backup master.

Another communication processing apparatus according to this inventionacts as a slave in a wireless communication network that comprises amaster which controls apparatus is characterized by having: adata-processing means for generating a packet containing data set asperformance parameters that are the performance values obtained of eachslave; a data-transmitting means for transmitting the packet generatedby the data-processing means, to the master; a data-receiving means forreceiving backup-master information from the master, the backup-masterinformation including address information corresponding to a backupmaster and synchronization information; a memory means for storing thebackup-master information received by the data-receiving means; and aconnection control means for performing a process of connecting theslaves to the backup master in accordance with the backup-masterinformation stored in the memory means.

In this communication processing apparatus, the data-processing means isconfigured to generate a packet that contains data containingperformance parameters of each slave. The performance parameters includeat least one of data items of remaining battery power, CPU performance,memory resource and RSSI, i.e., electric-field intensity.

In the communication processing apparatus according to the invention,the data-processing means is configured to set values for theperformance parameters that are data-processing performance itemsevaluated of each slave, in accordance with reference values set incommon in the wireless communication network.

In the communication processing apparatus according to this invention,the data-processing means may be configured to generate a packet storingdata in which performance parameters are set. The performance parametersinclude a data item representing whether the slave can be set as master.

In the communication processing apparatus according to the presentinvention, the wireless communication network is a wirelesscommunication network that performs Bluetooth communication, and thedata-receiving means may be configured to perform a process ofgenerating packets, each being a BNEP packet generated in accordancewith Bluetooth network encapsulation protocol (BNEP) and containing theperformance parameters.

In the communication processing apparatus according to the invention,the data-processing means may be configured to perform a process ofstoring the performance parameters in a BNEP packet generated inaccordance with Bluetooth network encapsulation protocol (BNEP).

In the communication processing apparatus according to this invention,the backup-master information is information containing a list thatcontains address information of a plurality of devices andsynchronization information, the devices being candidates for backupmaster, and the connection control means may perform a process ofconnecting the slaves to the backup master, in the order described inthe list.

A communication processing system according to the present inventionfunctions in a wireless communication network that comprises a masterwhich controls communication and at least one slave which communicatesthrough the master. The system is characterized by comprising: a masterwhich sets a backup master as a candidate for next master, on the basisof data containing performance parameters that are data-processingperformance items evaluated of each slave, and which suppliesbackup-master information about the backup master to each slave; andslaves which perform a process of figuring out data-processingperformance items evaluated of each slave in the form of performanceparameters and transmitting to the master, and which performs a processof receiving the backup-master information from the master and storingthe backup-master information in a memory means. Each of the slaves isconfigured to determine the next master on the basis of thebackup-master information after disconnected from the master, and toperform a connection process thereafter.

In the communication processing system according to this invention, theperformance parameters include at least one of data items of remainingbattery power, CPU performance, memory resource and RSSI, i.e.,electric-field intensity, all pertaining to the slave, and the master isconfigured to figure out a mater aptitude based on at least one of theperformance parameters transmitted from each slave.

In the communication processing system according to the invention, theperformance parameters include at least one of data items of remainingbattery power, CPU performance, memory resource and RSSI, i.e.,electric-field intensity, all pertaining to the slave, and the mastermay be configured to figure out the mater aptitude by performing anoperation in which a weight coefficient is applied to at least one ofthe performance parameters.

In the communication processing system according to the presentinvention, the master is configured to perform a process of storing thebackup-master information in a BNEP packet generated in accordance withBluetooth network encapsulation protocol (BNEP) and transmitting theBNEP packet to the slaves. The backup-master information includesaddress information corresponding to the backup master andsynchronization information.

In the communication processing system according to the invention, themaster may be configured to perform a process of transmitting abackup-master activation request packet to the backup master. Thebackup-master activation request packet requests for activation of thebackup master.

In the communication processing system according to the presentinvention, the master may be configured to perform a process of figuringout aptitude for a master based on the performance parameters receivedfrom the slave, generating a packet containing a list and transmittingthe packet to the slaves. The list contains synchronization informationand showing device-address information items in the order set inaccordance with the master aptitudes.

In the communication processing system according to the invention, themaster may be configured to perform a process of generating a packetcontaining a list and transmitting the packet to the backup master. Thelist contains synchronization information and address information itemsof the slaves that are devices constituting the wireless communicationnetwork.

A master-controlling method according to the present invention isdesigned for use in a communication processing apparatus which is to actas a master in a wireless communication network that comprises at leastone slave which communicates through the master. The method ischaracterized by having: a data-receiving step of receiving data fromeach of the slaves that are devices constituting the wirelesscommunication network, wherein capabilities of data processing for eachitem of evaluation are set as performance parameters in the data; adata-processing step of performing a process of figuring out aptitudefor a master based on the performance parameters received from the slaveand a process of determining one slave as a backup master that is acandidate for next master based on the master aptitude; and adata-transmitting step of transmitting backup-master informationcontaining address information and synchronization information, to eachslave of the wireless communication network, the address informationcorresponding to the backup master determined by the data-processingmeans.

In the master-controlling method according to the invention, theperformance parameters include at least one of data items of remainingbattery power, CPU performance, memory resource and RSSI, i.e.,electric-field intensity, all pertaining to the slave, and thedata-processing step is to figure out the mater aptitude based on atleast one of the performance parameters.

A master-connection method according to the present invention isdesigned for use in a communication processing apparatus which is to actas a slave in a wireless least one slave which communicates through themaster. The method is characterized by having: a data-processing step ofgenerating a packet containing data set as performance parameters thatare the performance values obtained of each slave; a data-transmittingstep of transmitting the packet generated in the data-processing step,to the master; a data-receiving step of receiving backup-masterinformation from the master, the backup-master information includingaddress information corresponding to a backup master and synchronizationinformation; a storing step of storing the backup-master informationreceived in the data-receiving step; and a connection-controlling stepof performing a process of connecting the slaves to the backup master inaccordance with the backup-master information stored in the storingstep.

In the master-connection method according to this invention, thedata-processing step is to generate a packet that contains datacontaining performance parameters of each slave. The performanceparameters include at least one of data items of remaining batterypower, CPU performance, memory resource and RSSI, i.e., electric-fieldintensity, all pertaining to the slave.

A computer program according to the present invention is designed tocontrol a communication processing apparatus which is to act as a masterin a wireless communication network that comprises at least one slavewhich communicates through the master. The computer program ischaracterized by describing: a data-receiving step of receiving datafrom each of the slaves that are devices constituting the wirelesscommunication network, wherein capabilities of data processing for eachitem of evaluation are set as performance parameters in the data; adata-processing step of performing a process of figuring out aptitudefor a master based on the performance parameters received from the slaveand a process of determining one slave as a backup master that is acandidate for next master based on the master aptitude; and adata-transmitting step of transmitting backup-master informationcontaining address information and synchronization information, to eachslave of the wireless communication network. The address informationcorresponds to the backup master determined in the data-processing step.

Another computer program according to this invention is designed toperform a process of connecting a communication processing apparatuswhich is to act as a slave in a wireless communication network thatcomprises a master which controls communication and at least one slavewhich communicates through the master. This program is characterized bydescribing: a data-processing step of generating a packet containingdata set as performance parameters that are the performance valuesobtained of each slave; a data-transmitting step of transmitting thepacket generated in the data-processing step, to the master; adata-receiving step of receiving backup-master information from themaster, the backup-master information including address informationcorresponding to a backup master and synchronization information; astoring step of storing the backup-master information received in thedata-receiving step; and a connection-controlling step of performing aprocess of connecting the slaves to the backup master in accordance withthe backup-master information stored in the storing step.

The present invention concerns a wireless communication networkcomprising a master that performs a communication control process and atleast one slave that performs communication via the master. In thenetwork, each slave figures out performance parameters that are itsperformance values and transmits the performance parameters to themaster. The master selects a backup master as a candidate for the nextmaster, on the basis of the performance parameters transmitted from theslave. The master then performs a process of supplying backup-masterinformation containing synchronization information and the address ofthe backup master selected. Hence, each slave can determine the nextmaster from the backup-master information, even if the master is removedfrom the network. Thus, the slave can be immediately connected to thenext master, and the user need not select a backup master. This shortensthe interruption of communication between the slaves and make itpossible to connect the slaves to the new master efficiently.

In the present invention, the performance parameters are thedata-processing performance items evaluated of each slave, such as theremaining battery power, CPU performance, memory resource and RSSI(electric-field intensity). On the basis of these information items themaster can select a slave as backup master, which can cope with theoperating condition of the network.

According to the invention, the backup-master information the mastersends to the slaves contains the synchronization information about thebackup master. Therefore, at least a part of the process of establishingsynchronization necessary for the reconstruction of the network need notbe carried out. This makes it possible to reconstruct the networkefficiently within a short time.

In the present invention, backup-master information that is a listshowing devices in the descending order of their master aptitudes may betransmitted to the slaves. Then, the slaves can have information about aplurality of backup masters. Namely, each slave can acquire theinformation of the other devices that constitute the piconet. Thus, ifany slave cannot be connected to the backup master having the highestmaster aptitude when the master is removed from the piconet, because thebackup master has been already removed from the piconet, it may beconnected to the backup mater that has the second highest masteraptitude.

According to the invention, a slave list may be transmitted the backupmaster. Then, in accordance with the slave list, the device selected asnew master can be connected to the slaves, one after another, after themaster is disconnected from the slaves. Each slave need not perform anyprocess to connect it to the master. The device selected as new mastercan use the Bluetooth-device addresses (BD ADDRs) contained in the slavelist and also the synchronization information, all transmitted from theprevious master. The new master can therefore efficiently establishconnection with the slaves. In the piconet thus set anew, the slaves cancommunicate with one another through the new master.

The computer program according to the invention can be provided as datathat can be read by general-purpose computer systems that can executevarious programs. The program can be provided in the form of acomputer-readable recording medium such as a CD (compact disk), an FD(floppy disk) or an MO (magneto optical disk) or via a communicationmedium such as a network. Once a computer system has read this program,it can carry out processes described in the program.

The system implementing this invention is a logical assembly of variouscomponents. All components of the system are not necessarily arrangedwithin the same housing.

The other objects of the invention and the advantages achieved by theinvention will be more apparent from the embodiments that will bedescribed below with reference to the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram showing an example of a network that implementscommunication that uses Bluetooth;

FIG. 2 is a diagram illustrating a Bluetooth module;

FIG. 3 is a diagram explaining a Bluetooth-device address;

FIG. 4 is a diagram explaining a communication processing apparatus thathas the Bluetooth module;

FIG. 5 is a diagram depicting the process sequence of setting up apiconet that comprises a device A set as master and device B to G usedas slaves;

FIG. 6A and FIG. 6B are diagrams explaining a BNEP packet;

FIG. 7 is a diagram representing the format of an expansion header to beset in the BNEP packet;

FIG. 8 is a diagram showing examples of performance parameters that theslaves may transmit to the master;

FIG. 9A is a diagram depicting an expansion type for the expansionheader set in a packet to be transmitted, the header containingperformance parameters, and FIG. 9B is a diagram showing a payload;

FIG. 10 is a diagram showing a list of backup masters (BMs) which may beselected, each in accordance with its master aptitude based onperformance parameters;

FIG. 11 is a diagram representing the process sequence, starting withthe transmission of backup-master (BM) information from the master to aslave, and ending with the use of a backup master as master;

FIG. 12A and FIG. 12B are diagrams illustrating an example of a packetof backup-master (BM) information, which is to be transmitted;

FIG. 13A and FIG. 13B are diagrams illustrating an example of abackup-master activation notice (BM Activation);

FIG. 14A and FIG. 14B are diagrams illustrating an example of a packetof net trigger notification (NET Trigger), which is to be transmitted;

FIG. 15 is a diagram depicting the sequence of spontaneously or forciblydisconnecting the slave having the backup-master information from theprevious master and then connecting the same to the new master inaccordance with the backup-master information;

FIG. 16 is a flowchart explaining the principle of the process that themaster performs to select a backup master and notify the selectionthereof;

FIG. 17 is a flowchart explaining the principle of the process that aslave performs to select a backup master and notify the selectionthereof;

FIG. 18A and FIG. 18B are diagrams illustrating an example of a packetto be transmitted, which is a BNEP packet containing a list ofbackup-master (BM) information items;

FIG. 19 is a diagram representing the process sequence in which a backupmaster is connected to each slave in accordance with a list; and

FIG. 20A and FIG. 20B are diagrams illustrating an example of a BNEPpacket to be transmitted, which contains a slave list.

BEST MODE FOR CARRYING OUT THE INVENTION

A communication processing apparatus, a communication processing system,a communication processing method, and a computer program, all accordingto this invention, will be described in detail with reference to theaccompanying drawings.

A communication system will be first described with reference to FIG. 1.The system comprises a piconet that is a wireless communication networkbased on communication processing apparatuses that constitute thepiconet.

As described above, the communication using Bluetooth is carried out ina network (piconet) that comprises a device called master, whichcontrols the communication, and a plurality of devices called slaves,which receive and transmit data through the master. In accordance withBluetooth, Bluetooth-device addresses are allocated to the devices, eachidentifying one device. Any device that is to transmit or receive datais identified with the Bluetooth-device address.

The piconet comprising a master and slaves can have up to seven slavesfor the master. All devices belonging to the piconet are synchronized interms of frequency axis (frequency hopping pattern) and time axis (timeslot).

FIG. 1 shows a piconet that comprises a personal computer (PC) 101 usedas master and some other devices used as slaves, i.e., a personalcomputer (PC) 121, a mobile telephone 122, a PDA (Personal DigitalAssistant) 123 and a video camera 124.

The piconet comprising one master and a plurality of slaves can be usedas an independent network not connected to any external network (inad-hoc mode). Alternatively, it can be connected to any other network,such as the Internet or other piconets, via the master (ininfrastructure mode).

The piconet is called “personal area network (PAN).” Each slave iscalled “PANU (PAN user).” The piconet may be connected to an externalnetwork (in infrastructure mode). In this case, the master makes routingof communication packets slaves, and also exchanges packets with theexternal network. Thus, the master is called “NAP (Network AccessPoint).” The piconet may not be connected to any external network (inad-hoc mode). If this is the case, the master makes routing ofcommunication packets between the slaves of the piconet. Thus, it iscalled “GN (Group Ad-hoc Network).”

Bluetooth defines specification known as “profile,” for any data to betransmitted or received by wireless communication, and for the procedureof wireless communication. The profile describes the service that eachdevice can provide. The PAN (Personal Area Network) profile describes amethod of achieving communication between the slaves of a piconet. Thedevices belonging to the piconet constituted on the basis of the PANprofile can transmit and receive various types of data, using thepiconet as a network.

The personal computer (PC) 101, personal computer (PC) 121 as a slave,mobile telephone 122, PDA (Personal Digital Assistant) 123 and videocamera 124, all shown in FIG. 1, incorporate a Bluetooth module each.They can transmit and receive various data items to and from oneanother, by means of wireless communication based on the Bluetoothstandards.

The devices, i.e., the master and the slaves, have a Bluetooth modulethat carries out wireless communication based on the Bluetoothstandards. More specifically, the module adopts a time-divisionmultiplex system that uses a 2.4-GHz ISM band to perform wirelesscommunication by means of frequency hopping spectrum diffusion in theISM band.

The configuration of the Bluetooth module will be described, withreference to FIG. 2. A CPU 201 loads the control program stored in a ROM202 into a RAM 203 and then controls a Bluetooth module 200 as a whole.The CPU 201 functions as a data-processing means or a communicationcontrol means. The CPU 201 to the RAM 203 are connected to one anotherby a bus 205. To the bus 205, there is connected a flash memory 204.

The flash memory 204 stores, for example, the names of the Bluetoothdevices set as master and slaves in the piconet, the Bluetooth-deviceaddresses unique to the Bluetooth devices, and the like.

The Bluetooth-device addresses are 48-bit indentifiers, each beingspecific, or unique, to one Bluetooth device. Hence, they are used invarious processes relating to the management of the Bluetooth devices.

To establish the devices synchronous in the piconet, for example, allslaves must have acquired the information about the frequency-hoppingpattern of the master. Each slave figures out the frequency-hoppingpattern beforehand, on the basis of the Bluetooth-device address of themaster.

To be more specific, a Bluetooth-device address consists of a 24-bitlow-address part (LAP), an 8-bit upper-address part (UAP), and a 16-bitnon-significant address part (NAP), i.e., the remaining 16 bits, as isillustrated in FIG. 3. Twenty-eight (28) bits, i.e., entire LAP (24bits) and the lowest 4 bits of the UAP, are used to figure out thefrequency-hopping pattern.

Each slave can figure out a frequency-hopping pattern from the 28-bitpart of the Bluetooth-device address of the master and a Bluetooth clocknotified by the master. Note that the Bluetooth-device address of themaster has been acquired by the paging performed to establish theintra-piconet synchronization.

Referring to FIG. 2 again, the flash memory 204 stores a link key andthe like. The link key authenticates Bluetooth devices that are tocommunicate with one another after the intra-piconet synchronization isestablished, or encrypts the data to be transmitted. The link key issupplied to the CPU 20, whenever necessary.

An input/output interface 206 controls the input and output of the datasupplied in accordance with the instructions from the CPU 201 and alsothe input and output of the data supplied from a base-band control unit207.

The base-band control unit 207 performs various controls and variousprocesses. The controls the unit 207 performs includes the control of atransceiver 208, the control of a link, the control of packets, thecontrol of logic channels, and the control of security. The processesthe unit 207 performs includes error-correction encoding and decodingand data randomizing. The unit 207 converts the data supplied from theinput/output interface 206, into analog data, which is output to thetransceiver 208. The unit 207 also converts a signal supplied from thetransceiver 208, into digital data. The digital data thus obtained isoutput to the input/output interface 206.

The transceiver 208 comprises a GFSK (Gaussian Frequency Shift Keying)modulation unit, a GFSK demodulation unit, a spectrum-diffusion unit, aninverse spectrum-diffusion unit or a hopping synthesizer unit, and thelike. It performs various processes on a signal supplied from thebase-band control unit 207 and supplies the signal processed to anantenna 209. It performs various processes on a signal supplied from theantenna 209, too, and outputs the signal processed to the basebandcontrol unit 207.

The GFSK modulation unit of the transceiver 208 selects the highlandcomponent of the data supplied from the baseband control unit 207, byusing a filter, and performs frequency modulation, or primarymodulation, on the high-band component, generating data. The data, thusgenerated, is output to the spectrum-diffusion unit. Thespectrum-diffusion unit switches the carrier frequency on the basis ofthe frequency-hopping pattern which has been figured out by using 28bits i.e., entire LAP (24 bits) and the lowest 4 bits of the UAP, asindicated above, and which has been notified from the hoppingsynthesizer unit. The spectrum-diffusion unit then performs spectrumdiffusion on the data it has received, and outputs the data to theantenna 209. In Bluetooth, the spectrum-diffusion unit is designed tocause frequency hopping every 625 microseconds, thereby to transmitdata.

The inverse spectrum-diffusion unit of the transceiver 208 performs thehopping of the receipt frequency, in accordance with thefrequency-hopping pattern notified from the hopping synthesizer unit.Thus, the inverse spectrum-diffusion unit acquires, for example, asignal transmitted from the slave with which the transceiver iscommunicating. The inverse spectrum-diffusion unit performs inversespectrum-diffusion on the signal acquired, thus reproducing the signaltransmitted from the slave, and output this signal to the GFSKdemodulation unit. The GFSK demodulation unit effects GFSK demodulationon the signal supplied from the inverse spectrum-diffusion unit,generating data. The data is output to the baseband control unit 207.

The transceiver 208 uses the 2.4-GHz band and transmits the signal thathas undergone spectrum diffusion, from the antenna 209. The transceiver208 outputs the signal received from the antenna 209, to the inversespectrum-diffusion unit.

Each of the communication processing apparatuses that constitute thepiconet has a module of the same configuration as the Bluetooth module200 shown in FIG. 2. Each communication processing apparatus carries outthe processes described above, thus accomplishing data communication.

The communication processing apparatuses constituting the piconet, i.e.,the devices each having a Bluetooth module of the type described above,will be described with reference to FIG. 4. FIG. 4 is a block diagramshowing a personal computer that is an example of a communicationprocessing apparatus that acts as master or a slave in the piconet. Theconfiguration shown in FIG. 4 will be explained below.

A CPU (Central Processing Unit) 301 performs various processes inaccordance with the programs stored in a ROM (Read Only Memory) 302, anHDD 304, or the like. Namely, it works as a means or a communicationcontrol means. A RAM 303 stores, if necessary, the programs and datathat the CPU 301 executes and uses. The CPU 301, ROM 302, RAM 303 andHDD 304 are connected to one another by a bus 305.

To the bus 305, an input/output interface 306 is connected. To theinput/output interface 306 there are connected an input unit 307, anoutput unit 308, a communication unit 309, and a drive 310. The inputunit 307 comprises a keyboard, switches, buttons, and a mouse, which areoperated by the user. The output unit 308 comprises an LCD or a CRT,speakers and the like. The communication unit 309 is the Bluetoothmodule described with reference to FIG. 2 and functions as a means fortransmitting and receiving data. The drive 310 can hold a removablerecording medium 311, such as a magnetic disc, an optical disc, anopt-magnetic disc, or a semiconductor memory, and can read and writedata in and from the removable recording medium 311.

Shown in FIG. 4 is a personal computer (PC), which is an example of acommunication processing apparatus that may be used as master or a slavein the piconet illustrated in FIG. 1. The communication processingapparatus used as master or a slave in the piconet is not limited toPCs, nevertheless. As seen from FIG. 1, the communication processingapparatus can be a mobile communication terminal such as a mobiletelephone or a PDA, a video camera, or any other type of aninformation-processing apparatus. That is, the device has a uniquehardware

As will be detailed below, the communication processing apparatus thatworks as master in this invention needs to have data-receiving means, adata-processing means, and a data-transmitting means. The data-receivingmeans receives, from each slave, the data containing performanceparameters that represent the data-processing performance itemsevaluated of the slave. The data-processing means figures out the masteraptitude of each slave from the performance parameter it has receivedfrom the slave. Based on the master aptitudes thus figured out for allslaves, the data-processing means selects one slave as a backup master,i.e., the next master. The data-transmitting means transmits, to allslaves, the backup-master information containing the address informationand synchronization information about the backup master determined bythe data-processing means. These components are the hardware items thatare illustrated in FIG. 2 and FIG. 4. The processes that the componentsperform will be explained below in detail.

The communication processing apparatus according to the invention, usedas a slave, is set as one that comprises a data-processing means, adata-transmitting means, data-receiving means, a memory means and aconnection control means. The data-processing means generates a packetcontaining performance parameters that represent the data-processingperformance items evaluated of the slave. The data-transmitting meanstransmits the packet generated by the data-processing means, to themaster. The data-receiving means receives, from the master,backup-master information containing the address information andsynchronization information about a device that corresponds to a backupmaster. The memory means stores the backup-master information that thedata-receiving means has received. The connection control means connectsthe slave to the backup master in accordance with the backup-masterinformation that the memory means has stored. These components are thehardware items that are illustrated in FIG. 2 and FIG. 4. The processesthat the components perform will be explained below in detail.

In a piconet of the type that comprises one master and a plurality ofslaves as is illustrated in FIG. 1, each communication processingapparatus, used as either as master or a slave, performs a sequence ofsetting a network, as will be described below. The sequence starts withthe process of setting one of the slaves set in the piconet, as a backupmaster (BM), i.e., a candidate for the master, and ends with the processof making the backup master takes over the master function from themaster if the master is removed from the network, to control thecommunication between the slaves belonging to the same piconet.

FIG. 5 is a diagram depicting the process sequence of setting up apiconet that comprises a device A set as master and devices B to G usedas slaves.

First, in Step S11, the device B functioning as a slave transmits aninquiry by broadcasting. The broadcast transmission of the inquiry isthe first-stage process that the master performs to establish theintra-piconet synchronization after determining that slaves exist aroundit. At this time, however, it is not clear whether a master exists inthe piconet. This is why the device B functioning as a slave acts as aprovisional master and transmits the inquiry by broadcasting. That is,the inquiry is transmitted by broadcasting, in order to confirm theexistence of the master and to acquire the address of the master (i.e.,Bluetooth-device address: BD-Address) and also synchronizationinformation transmitted from the master.

In Step S12, the device A, which acts as master and which has receivedthe inquiry, supplies its address (i.e., Bluetooth-device address:BD-Address), clock information and the like to the device B. The clockinformation servers to achieve synchronous communication between themaster and any slave.

Next, in Step S13, the device B functioning as a slave performs pagingto the device A that is acting as master. The paging is the second-stageprocess that is performed to establish the intra-piconetsynchronization. This process accomplishes synchronization between themaster and a specific slave, that is, between the device B and thedevice A in this instance.

“Paging” is a process of first designating a specific Bluetooth deviceto demand that Bluetooth communication be started, and then transmittingand receiving various data items to establish the synchronization. Moreprecisely, the master and the slave exchange their attribute informationitems (FHS packets). The master and the slave are rendered synchronousin terms of frequency axis and time axis, on the basis of the attributeinformation items exchanged.

In the piconet, the master and the slave that carry out Bluetoothcommunication between them have a clock (Bluetooth clock) each. Theslave needs to make its clock comply with the clock of the master (i.e.,Bluetooth clock). It is paging that causes the clock of the slave tocomply with that of the master. The paging is effected in three phases.The first phase is page-transmitting. The second phase is page-scanning.The third phase is page-responding. The paging, thus effected, adjuststhe clock of the master and the clock of the slave to each other,establishing the synchronization. At this time, the device B and thedevice A operate in synchronism, acting as master and a slave,respectively. However, the device A has been set as master. A processis, therefore, performed to cause the devices A and B to operate insynchronism, respectively as master and a slave. This process is called“master-slave conversion.”

Then, in Step S14, a process is performed between the master (device A)and the slave (device B), which have been made to operate insynchronism, by using SDP (Service Device Protocol). SDP determinesservice that is effective at this time. SDP is a protocol that searchesfor the function or service that the master and slave, used ascommunication processing apparatuses in the piconet, can provide. SDPcan therefore determine the service that the master and slave canprovide, such as reproduction of music data, access to the network, orthe like. Any apparatus that has a Bluetooth module stores, in adatabase, the information about the service it can offer, reads thisservice information from the database, and provide the serviceinformation.

Next, in Step S15, the process of setting up security is carried outbetween the master (device A) and the slave (device B). To be morespecific, the security setup process is to set a link key that managesthe mutual security of the master (device A) and slave (device B). Thelink key is applied to authenticate the master and the slave, both beingBluetooth devices that communicate with each other, and to encrypt thedata to be transmitted or received from and to either Bluetooth device.

Hitherto, the above-mentioned sequence of processes is performed betweenthe master and each slave in the piconet, thus achieving inquiring andpaging to set a communication environment for the master and each slave.Once the communication environment is so set, SDP determines the serviceinformation and sets the link key, thereby establishing security inpreparation for the communication between the master and the slave.Thereafter, the master first activates the service when it receives acommunication request for the service selected by the slave, and thenstarts the process of establishing the communication.

After the preparation process, the communication is effected in thepiconet, through the master. After the use of the service any slaveprovides is started, the master (device A) may be removed from thenetwork or the power may run out in the battery. In this event, theslaves can no longer communicate with one another via the master. Toresume the communication between the slaves, the user needs to set a newmaster, or reconstruct the piconet.

To resume the communication, the following steps S16 et seq. are carriedout in the present invention:

-   -   (1) Process of acquiring performance parameters, or performance        information, from the slaves, by means of the master.    -   (2) Process of setting the next master, or backup master (BM),        on the basis of the performance parameters acquired from the        slaves.    -   (3) Process of supplying the backup-master (BM) information to        each slave.

These processes will be described below in detail. In the sequencediagram of FIG. 5, the master (device A) performs a BNEP setup processfor the slave (device B) that has completed the synchronization, thesecurity setup and the SDP process.

BNEP stands for “Bluetooth Network Encapsulation Protocol.” Thisprotocol makes it possible to transfer Ethernet packets in the form ofcapsules on the Bluetooth L2CAP. BNEP packets are packets that are usedas control packets or data packets to be transmitted by using BNEP.

BNEP packets have the configuration shown in FIG. 6A and FIG. 6B. FIG.6A represents the BNEP packet and the header affixed to the BNEP packet.FIG. 6B depicts the configuration of the BNEP packet.

In the header to the BNEP packet, a BNEP type and an extension flag areset. The BNEP type may be [CONTROL] or the like, which indicates thatthe packet is a [GENERAL ETHERNET] packet, a [COMPRESSED ETHERNET] or acontrol packet. The extension flag is information that indicates whetherthe BNEP packet has an extension header (1=header existing, 0=header notexisting). A header that accords with the BNEP type follows theextension flag. Further, an extension header is added, if any. A payloadthat accords with the BNEP type is stored, next to the extension flag.

FIG. 6B illustrates an example of a payload. The BNEP packet comprises adestination address, a source address, a networking protocol type, anextension header, if any, and a payload. The destination address and thesource address are, for example, Bluetooth-device addresses (BDaddresses). The networking protocol type is, for example, a protocoltype that accords with the Ethernet.

In the present invention, each slave in the piconet transmits a BNEPpacket (or control packet) to the master, the packet containing theperformance parameter representing the performance value of the slave.The master evaluates the master aptitude that the slave has, from theperformance parameter it has received from the slave. From the masteraptitude thus evaluated, the master then determines whether the slavecan be used as next master and determines which slave should be used asa backup master (BM).

FIG. 7 shows the format of the extension header that is added to theBNEP packet. The extension header contains an extension type, anextension flag, an extension length and a payload (extension payload).The extension type represents the type of transmission of a performanceparameter or the type of transmission of a backup-master information andthe like. The extension flag indicates whether the packet has any otherextension header (1=header existing, 0=header not existing). Theextension length represents the length of the extension header. Acontrol packet, for example, can be added, as an extension header, toany other BNEP packet.

FIG. 8 shows examples of performance parameters to be transmitted from aslave to the master in the network (i.e., piconet). The performanceparameters are values evaluated of the slave. They can be used asindicators to determine whether the data-processing performance items ofthe slave enable the slave to be selected as master.

In the examples shown in FIG. 8, the remaining battery power, the CPUperformance, the memory resource, the electric-field intensity (RSSI:Radio Signal Strength Indicator), and the information showing whetherthe slave can be set as master are the data-processing performance itemsthat are used as performance parameters. The performance parametersinclude parameter identifiers 0×01 to 0×05, respectively. Note that “0×”means that each parameter identifier is a hexadecimal number.

Of the performance parameters, the remaining battery power to the RSSImay have a value ranging from 0×00 to 0×FF (1 byte=256 possible values)on the basis of the parameter-evaluation reference values held inslaves. These parameters may indicate the lowest performance=00, and thehighest performance=FF.

More precisely, the remaining battery power is set as a performanceparameter having value FF indicating the highest performance, if theslave is connected to an AC power supply and is therefore continuouslysupplied with electric power. The slave may use a rechargeable battery,a cell or the like. In this case, the performance parameter ranges from00 to FF in accordance with the power that remains in the battery, cellor the like. These reference values are held, as common data, in allslaves. necessary, to the slaves.

The CPU performance is a performance parameter that is set in accordancewith the type and operating clock frequency of the CPU. This performanceparameter has a specific value set, also in accordance with the datacommon to all slaves.

The memory resource is a performance parameter that is set in accordancewith the storage capacity which remains in the flash memory and RAMprovided in the slave and which can be effectively used. Thisperformance parameter has a specific value set also in accordance withthe data common to all slaves.

The electric-field intensity (RSSI) is a performance parameter that isset in accordance with the electric-field intensity (RSSI) determinedfrom the condition of the Bluetooth communication between the slave andthe master. This performance parameter has a specific value that is setalso in accordance with the data common to all slaves.

The master aptitude, or master-aptitude information, is a performanceparameter that has a specific value if the slave cannot be set as masterbecause it cannot make routing of packets between the other slaves orbecause the user has set it as a slave that cannot be used as master. Ifthe slave can be used as master, the master aptitude has anotherspecific value indicating that the slave can be set as master. Thisperformance parameter may have a value ranging from 0×00 to 0×FF.Alternatively, it may have the value indicating that the slave can beused as master, or the value indicating that the slave cannot be used asmaster.

As described above, the piconet comprising one master and a plurality ofslaves can be an independent network (in ad-hoc mode) that is notconnected to any external networks, or a network (in infrastructuremode) that is connected to any other network, such as the Internet oranother piconet, through the master. While the piconet remains connectedto any other network (in infrastructure mode), the master makes routingof packets between the slaves constituting the piconet, thus achievingthe packet exchange within the piconet, and also accomplishing packetexchange with the external networks. Thus, the master is called “NAP(Network Access Point).” While the piconet remains an independentnetwork (in ad-hoc mode), not connected to the external networks, themaster makes routing of packets between the slaves constituting thepiconet. In this case, the master is called “GN (Group Ad-hoc Network).”

The master may be connected to any other network, thus functioning as aNAP, or may not be connected to any other network, thus functioning as aGN only. The information showing whether the master can function as aNAP or function as a GN only can be set as master-aptitude information.In this case, the master-aptitude information has one of the followingfour performance-parameter values:

(a) Non-master aptitude

(b) Master aptitude, either as NAP and GN

(c) Master aptitude, as GN only

(d) Master aptitude, as NAP only

FIG. 8 shows the remaining battery power, CPU performance, memoryresource, electric-field intensity (RSSI: Radio Signal StrengthIndicator) and master aptitude, i.e., the information items that areexemplified as performance parameters. Only some of these informationitems may be applied. Otherwise, information items other than these maybe applied.

To transmit the information representing the values of these performanceparameters to the master, an extension header (see FIG. 8) descried withreference to FIG. 7 is added to a BNEP packet. The parameter identifiers(PARAMs) and the values (indices) of the performance parameters areincorporated, as a payload, into the extension header. The BNEP packetis then transmitted to the master.

The extension type and payload of the extension header of a packet whichis to be transmitted and which contains the performance parameters willbe described, with reference to FIG. 9A and FIG. 9B.

As FIG. 9A shows, the extension type is set to [BNEP Extension Control],which indicates that a control packet should be transmitted.

As 9B depicts, the payload (Extension Payload) contains head data andsubsequent data. The head data consists of [NET PARAM] and [PARAMNUM].[NET PARAM] indicates that the payload contains performance parametersto be transmitted, and [PARAMNUM] represents the number of parameterscontained in the payload. The subsequent data consists of differentperformance parameters, each composed of a parameter identifier (PARAM)and a performance parameter value (INDEX). These performance parametersmay be transmitted in the form of an ordinary control packet.

As seen from FIG. 9B, the number (PARAMNUM of parameters to betransmitted is [0×05] for the head data, indicating that the payloadcontains five parameters. The data item [0×01] [0×2C] follows [0×05]. Asis clear from FIG. 8, [0×01] is the remaining battery power, and [0×2C]is the value of the performance parameter for the remaining batterypower.

Further, [0×02] [0×C3] indicates that the value of the performanceparameter of the CPU performance is [0×C3]; [0×03]. [0×38] indicatesthat the value of the performance parameter of the memory resource is[0×38]; and [0×04] [0×8A] indicates that the value of the performanceparameter of RSSI is [0×8A]. Moreover, [0×05] [0×01] is data that is aresponse to the inquiry of whether the slave can be set as master. Forexample, [0×01] indicates that the slave can be master that can functionas both NAP and GN.

Referring to the sequence diagram of FIG. 5 again, the device B workingas a slave transmits a control packet to the master (device A). Theextension header of the control packet contains a payload that consistsof the above-mentioned performance parameters. Upon receipt of thecontrol packet, the master (device A) starts performing the serviceassigned to it. Namely, the master performs the process of establishingcommunication (Step S17).

Steps S11 to S17 are carried out for all the slaves provided in thepiconet. That is, the above-described procedure is performed between thedevices B to G functioning as slaves, on the one hand, and the master(device A), on the other. The master accumulates the values of theperformance parameters of each slave existing in the piconet. When a newslave may join the piconet, the same procedure is executed, and themaster acquires performance parameters from the new device added to thepiconet. Any slave device may change in operating condition. In thiscase, the slave device transmits a control packet or BNEP packet, theextension header of which contains the performance parameters updated,to the master.

In accordance with the performance parameter acquired from the slaves,the master sets one of the slaves, as a backup master (BM), or acandidate for master.

The process of setting a slave as a backup master (BM) will be explainedbelow. Assume that the master has already acquired the parameters, i.e.,the remaining battery power to the master aptitude, from all slaves.

First, any slave whose master aptitude is negative is rejected as abackup-master (BM) candidate. The remaining slaves, each having anaffirmative master aptitude, are compared in terms of the otherperformance parameters. In other words, the master first figures out themaster aptitudes of these slaves based on the performance parameters ithas received from the slaves and then selects one of the slaves asbackup master, i.e., the next master, in accordance with the masteraptitudes figured out.

More specifically, weight coefficients (α to δ) are assigned to (1)remaining battery power to (4) RSSI, respectively. The weightcoefficients are applied to figure out the master aptitude of each slavefrom the parameters (1) to (4) acquired. The master aptitude of theslave (device B), B(BM), for example, is figured out as expressed by thefollowing equation:B(BM)=αB1+βB2+γB3+δB4where B1, B2, B3 and B4 are (1) remaining battery power, (2) CPUperformance, (3) memory resource and (4) RSSI of the slave (device B).

The master aptitudes C(BM) to G(BM) of the other slaves, i.e., devices Cto G, are figured out in the same way as that of the slave (device B).The master can adjust the weight coefficients α to δ, to select oneslave as backup master, in accordance with the operating condition ofthe network.

After figuring out the master aptitudes of all slaves, the masterselects one of the slaves, which has the highest of the master aptitudesB(BM) to G(BM) figured out, as backup master (BM). At the same time, themaster generates a list that shows the slaves in the descending order oftheir master aptitudes (i.e., possibility as being used as backup master(BM)).

FIG. 10 shows such a list. This list shows the slaves arranged in thedescending order of the master aptitude. The list contains the address(Bluetooth device (BD) address), page scan mode that is connectioninformation and clock offset information of each slave. Theseinformation items have been acquired in the inquiry process and thepaging process, both included in the sequence illustrated in FIG. 5.

The master figures out master aptitudes for the slaves, based on theperformance parameters it has acquired from the slaves. The masterselects, as backup master (BM), the slave for which the highest masteraptitude has been obtained. Next, the master transmits the informationconcerning the backup master (BM), or the slave thus selected, to eachslave.

FIG. 11 shows the sequence that begins with the transmission of thebackup-master (BM) information from the master to the slaves and endswith the transition of master function to the backup master. Withreference to the sequence diagram, the processes constituting thissequence will be described in detail.

In Step S21 shown in FIG. 11, the master transmits the information aboutthe device for which the highest master aptitude has been figured outand which has been therefore selected as backup master (BM), to eachslave. Thus, the master notifies BM selection to the slaves. Thebackup-master (BM) information is transmitted to the slaves, as a dataitem contained in a BNEP control packet.

The configuration of the BNEP control packet containing thebackup-master (BM) information will be explained with reference to FIG.12.

As FIG. 12A shows, [BNEP CONTROL] is set in the BNEP type (BNEP Type),indicating that the packet is a control packet.

As FIG. 12B depicts, [NET BM SELECTION] is set in the BNEP payload,indicating that the backup master (BM) information is being transmitted.In the BNEP payload, [NET BM SELECTION] is followed by Bluetooth-deviceaddress (BD ADDR), page scan mode (PageScanMode), clock offset(ClockOffset), and connection backoff time (Connect Backoff Time). TheBluetooth-device address is the address of the slave selected as backupmaster (BM). The page scan mode is information that must be used to makethe slaves operate in synchronism with the backup master (BM). Theconnection backoff time causes the slaves to make connection requests(Page) at different times to the backup master (BM), i.e., the newmaster. The control packet may be transmitted in the form of anextension header that is added to the BNEP packet.

The connection backoff time (Connect Backoff Time) sets differentbackoff times to the slaves so that the slaves may not make connectionrequests at the same time. Nevertheless, the backoff time need not benotified to each slave if backoff times based on random numbers are setto the slaves. In this case, the slaves will not be connected to themaster at the same time.

In Step S21 shown in the sequence diagram of FIG. 11, the backup-masterinformation is transmitted to all slaves. The master (device A) may besoon removed from the piconet thereafter. In this case, in Step S22, themaster transmits a backup-master activation notice (BM Activation) tothe device B that has been selected as backup master.

A configuration that the packet containing the backup-master activationnotice (BM Activation) may have will be described, with reference toFIG. 13A and FIG. 13B.

As FIG. 13A shows, [BNEP Control] is set in the BNEP type (BNEP Type),indicating that the packet is a control packet.

As FIG. 13B depicts, [NET BM Activation] is set in the BNEP payload(BNEP Payload) indicating the transmission of a backup-master activationnotice. Further, [Target UUID)] is set in the BNEP payload, following[NET BM Activation]. [Target UUID] is type information that showswhether the master should be as a NAP (Network Access Point) or a GN(Group Ad-hoc Network). This control packet may be transmitted in theform of an extension header that is added to the BNEP packet.

As indicated earlier, a NAP (Network Access Point) is the master in anetwork (piconet) that is connected to any other network (ininfrastructure mode). The NAP makes routing of packets between theslaves in the piconet. That is, it performs packet exchange within thepiconet. In addition, the NAP effects packet exchange between thepiconet and any external network connected to the piconet. If thepiconet is independent, not connected to any external network (in Ad-hocmode), the master functions as a GN (Group Ad-hoc Network) to makerouting of communication packets between the slaves within the piconet.

Referring the sequence diagram of FIG. 11 again, the master (device A)transmits the backup-master information again to each slave just beforethe master is removed from the piconet. This is because a new slave maybe incorporated into the piconet and the master (device A) may thereforereceive performance parameters from the new slave and figure out masteraptitudes for all existing slaves. Thus, the master sends the latest, orupdated backup-master information to all slaves. Moreover, the mastertransmits a notice of net trigger (NET Trigger), informing that it willstop offering service as master.

A configuration of the notification of the net trigger (NET Trigger)will be described with reference to FIG. 14A and FIG. 14B.

As illustrated in FIG. 14A, [BNEP Control] is set in the BNEP type (BNEPType), indicating that the packet is a control packet.

As shown in FIG. 14B, [NET Trigger] is set in the BNEP payload (BNEPPayload), indicating the transmission of a notice of the net trigger(NET Trigger). Further, [BD ADDR], [PageScanMode], [ClockOffset],[Target UUID] and [Delay before reconnect] are set in the BNEP payload,following [NET Trigger]. [BD ADDR] is the Bluetooth-device address ofthe backup master (BM) selected. [PageScanMode] is information that mustbe used to make the slaves operate in synchronism with the backup master(BM). [Target UUID] is type information that shows whether the mastershould be as a NAP (Network Access Point) or a GN (Group Ad-hocNetwork). [Delay before reconnect] causes the slaves to make connectionrequests (Pages) at different times to the backup master (BM), i.e., thenew master. This control packet may be transmitted in the form of anextension header that is added to the BNEP packet.

Like the connection backoff time (Connect Backoff Time) described above,[Delay before reconnect], or connection delay time, sets differentbackoff times to the slaves so that the slaves may not make connectionrequests at the same time. Nevertheless, the backoff time need not benotified to each slave if backoff times based on random numbers are setto the slaves. In this case, the slaves will not be connected to themaster at the same time.

Next, in Step S24, each slave is disconnected (Disconnect) from themaster (device A) which will be removed from the piconet, if the nettrigger (NET Trigger) or the like has notified that the master will beremoved from the piconet. If the net trigger has not notified theeventual removal of the master, no apparent disconnection of slaves willbe performed when the power supply to the master is abruptly turned off.In this case, an ordinary timeout signal is generated, which indicatesthat the slaves have been disconnected from the master. If the master isabruptly removed from the piconet, the net trigger (NET Trigger) may notbe notified in some cases.

In these cases, each slave has received the backup-master (BM)information transmitted to it in Step S21, i.e., the step of setting thepiconet. Each slave can therefore perform paging (Page) to the backupmaster (BM) on the basis of the information it has received. Thebackup-master (BM) information contains synchronization information.Thus, each slave can be efficiently connected to the backup master,without carrying out the process of initially establishingsynchronization.

The sequence of spontaneously or forcibly disconnecting the slave havingthe backup-master information from the previous master and thenconnecting the same to the new master in accordance with thebackup-master information will be explained with reference to FIG. 15.

The sequence diagram of FIG. 15 illustrates how the device B operates asmaster when it receives the master activation notice from the device Aafter the previous master (device A) is removed from the piconet andthen the device B is selected as backup master.

In Step S31, the slaves (device C to device G) perform paging (Page) tothe new master (device B). In the ordinary connection process, theslaves must transmit an inquiry to search for the master and mustacquire prescribed synchronization information, as has been describedwith reference to FIG. 5. In this case, the slaves have received thebackup-master information from the previous master (in Steps S21 to S23shown in FIG. 11). That is, they have acquired the address of the deviceB set as backup master and the synchronization information. The slavescan therefore communicate with the master by carrying out paging (Page);they need not transmit an inquiry. In the paging, the master and eachslave exchange their attribute information items (i.e., FHS packets).The attribute information items, thus exchanged, render the master andthe slave synchronous in terms of frequency axis and time axis.

Next, in Step S32, the slaves (device C to device G) transmit BNEPpackets to the new master (device B), notifying performance parametersto the new master. This process is similar to Step S16 of the processsequence of FIG. 5. The slaves transmit performance parameters shown inFIG. 8 to the new master, in the form of packets that have theconfigurations described with reference to FIG. 6, FIG. 7 and FIG. 9.

Thereafter, the new master figures out master aptitudes for the slaves,based on the performance parameters received, in the same way as hasbeen explained above. The new master selects one of the slaves as nextbackup master (BM). The new master then notifies the address of theslave selected as next backup master to the other slaves, together withthe synchronization information of this slave.

In the piconet, the master thus selects one slave as backup mater, i.e.,candidate for the next master, in accordance with the performanceparameters it has received from the slaves. The master then notifies theaddress and synchronization information of the backup master, asbackup-master information, to the slaves. From the backup-masterinformation, the slaves can determine which device is the next master.Hence, synchronization can be immediately secured between the new masterand the slaves, on the basis of the address information andsynchronization information, both contained in the backup-masterinformation. This minimizes the interruption of communication betweenthe devices that constitute the piconet when the master device isremoved from the piconet.

In the process sequence of FIG. 15, no steps are illustrated betweenStep S31 and Step S32. Nonetheless, the SDP (Service Device Protocol)process and the security-setup process are carried out after Step S31and before Step S32.

The process of selecting a backup master and notifying the backup masterselected will be described in detail. More precisely, the stepsperformed by the master will be described with reference to theflowchart of FIG. 16, and the steps performed in a slave will bedescribed with reference to the flowchart of FIG. 17.

FIG. 16 is a flowchart explaining the gist of the process that the matercarries out in the piconet. First, in Step S101, the master receivesperformance parameters from each slave. The parameters represent thevarious performances of the slave, such as the remaining battery power,the CPU performance and the like.

In Step S102, the master determines whether it has received performanceparameters from all slaves. If it has received the parameters from allslaves, the master evaluates the master aptitude of each slave on thebasis of the performance parameters it has received from the slave. Tobe more specific, the master adjusts weight coefficients in accordancewith the operating condition of the network, applies them to the variousperformance indicators of each slave, such as the remaining batterypower and the CPU performance, and figures out mater aptitudes for eachslave, from the performance indicators thus weighted. Then, in StepS103, the master selects the slave having the highest mater aptitudes,as backup master.

In Step S104, the master transmits the information of the backup master,i.e., the slave selected in accordance with its master aptitude, to theslaves. That is, the master transmits the address information andsynchronization information of the backup master to the slaves. Themaster carries out the process shown in this flowchart, every time itreceives performance parameters from any new slave or any existingslave. The master can, therefore, select a slave that can mostappropriately operate as backup master in the present operatingcondition of the network.

How each slave operates in the piconet will be described, with referenceto FIG. 17. In Step S201, the slave transmits performance parameters tothe master. This step is to transmit the parameters representing thevarious performance items of the slave, such as the remaining batterypower and the CPU performance, and contained in the extension header ofa BNEP packet.

Next, in Step S202, the slaves receive backup-master information fromthe master. This information is stored into the memory unit provided inthe slave. In Step S203, the slave determines whether it has beendisconnected from the master. The slave may be spontaneouslydisconnected from the master when it receives a net trigger from themaster (in Step S23 shown in FIG. 11) or disconnected due to an event onthe part of the master, e.g., the power running-out of the battery orthe removal of the master from the network. The operating condition ofthe slave may change, changing the performance parameters thereof. Ifthis happens, Step S201 may be carried out.

In any case where the slave is disconnected from the master, it goes toStep S204. In Step S204, the slave performs the paging (Page) withrespect to the backup master that is the new master. Thus, the backupmaster functions as master of the piconet.

Further, in Step S205, the slave transmits its performance parameters tothe new master.

As described above, the slave receives the address information andsynchronization information of the backup master from the backup masterand holds them as backup-master information. From the backup-masterinformation, the slave can determine which device is the next masterafter the master is removed from the piconet. This enables the slave tobe connected to the new master and operate in synchronism therewithefficiently.

In the instance described above, the backup-master information that themaster gives the slaves is concerned with only the device that has thehighest master aptitude. Instead, the information may be a list showingthe devices in the descending order of master aptitude. Once each slavehas received this list as backup-master information, it acquiresinformation about the other devices constituting the piconet. Thus, ifany slave cannot be connected to the backup master having the highestmaster aptitude because this backup master has been removed from thepiconet prior to the master, it can be connected to the backup masterthat has the second highest master aptitude.

A configuration of a BNEP packet, which contains the backup-masterinformation provided in the form of such a list and which is to betransmitted to the slaves, will be described with reference to FIG. 18Aand FIG. 18B.

As FIG. 18A shows, [BNEP Control] is set in BNEP type (BNEP Type),indicating that the packet is a control packet.

As FIG. 18B depicts, [NET BM LIST] and [LIST NUM] are set in the BNEPpayload (BNEP Payload). [NET BM LIST] shows that the information to betransmitted is a list of backup masters (BMs). [LIST NUM] represents thenumber of the backup masters (BMs) shown in the list. Sets of data items[BD ADDR], [PageScanMode], [ClockOffset] and [Connect Backoff Time] areset in BNEP payload (BNEP Payload), after the [NET BM LIST] and [LISTNUM]. These data-item sets correspond to the backup masters shown in thelist, respectively. The data items of each set are arranged in the orderthey are mentioned. [BD ADDR] represents the Bluetooth-device addressesof the backup masters (BMs). [PageScanMode] is information that enablesthe slaves to operate in page scan mode (PageScanMode), namely insynchronism with any backup master (BM). [Connect Backoff Time] makesthe slaves to transmit connection requests (Pages) at different times tothe backup master (BM), i.e., the new master. This control packet may betransmitted in the form of an extension header that is added to the BNEPpacket.

In the embodiment described above, a slave performs the connectionprocess with respect to the new master, i.e., the backup master.Instead, the backup master may carry out the connection process inaccordance with the list, with respect to a slave. That is, the backupmaster may transmit the slave information about the slaves provided inthe piconet so that it may be connected to a slave after the previousmaster is removed from the piconet.

The sequence of the connection process the backup master performs willbe explained, with reference to FIG. 19.

The sequence diagram of FIG. 19 illustrates the steps that are performedafter the device A, which is the existing master, selects the device Bas backup master in accordance with the performance parameters.

In Step S51, the device A, or existing master, transmits to the deviceB, or backup master, a BNEP packet that contains a slave list (SlaveList).

A configuration that the BNEP packet containing the slave list may havewill be described with reference to FIG. 20A and FIG. 20B.

As seen from FIG. 20A, [BNEP Control] is set in the BNEP type (BNEPType), indicating that the packet is a control packet.

As FIG. 20B shows, [NET SLAVES LIST] and [LIST NUM] are set in thepayload (BNEP Payload). [NET SLAVES LIST] indicates that the list is aslave list. [LIST NUM] represents the number of slave information itemsto be transmitted in the form of a list. Sets of data items [BD ADDR],[PageScanMode], [ClockOffset] and [Connect Backoff Time] are set in thepayload (BNEP Payload), after the [NET SLAVES LIST] and [LIST NUM].These data-item sets correspond to the slaves shown in the list,respectively. The data items of each set are arranged in the order theyare mentioned. [BD ADDR] represents the Bluetooth-device addresses ofthe slaves. The next data items, [PageScanMode], are information thatenables the backup master to operate in synchronism with the slaves.[Connect Backoff Time] makes the new master to transmit connectionrequests to the slaves at different times. This control packet may betransmitted in the form of an extension header that is added to the BNEPpacket.

The new master may set the connection backoff time (Connect BackoffTime) by itself. In this case, the connection backoff time need not becontained, as notification data, in the BNEP packet.

The description will be further made, with reference to the processsequence shown in FIG. 19 again. In Step S51 in the sequence diagram ofFIG. 19, the above-mentioned slave list is transmitted to the backupmaster (device B). When the master (device A) is thereafter removed fromthe piconet, it transmits a backup-master activation notice (BMActivation) to the device B that has been selected as a backup master,in Step S52. The backup-master activation notice (BM Activation) has theconfiguration described with reference to FIG. 13. If any new slave isadded to the piconet, the list data is updated to contain theinformation about the new slave and is transmitted to the backup master(device B).

Next, in Step S53, a disconnection process (Disconnect) is carried outto disconnect the master (device A) from the slaves. This disconnectionis either a spontaneous one or a forced one made by the master.

After the master is disconnected from the slaves, the device B, i.e.,new master, performs the process of connecting itself to the slaves(devices C to G), one after another on the basis of the slave it hasreceived. As new master, the device B can efficiently establishconnection with each slave, by using the address, i.e., Bluetooth-deviceaddress (BD ADDR), and the synchronization information, which arecontained in the slave list transmitted from the previous master (deviceA).

In the piconet thus set anew, the slaves start communication with thenew master.

The present invention has been described in detail, with reference to aspecific embodiment. Nonetheless, it is obvious that any person skilledin the art can modify or replace the embodiment without departing fromthe scope and spirit of this invention. That is, the embodiment describeabove is nothing more than an example of the invention. To understandthe gist of this invention, the claims set forth at the end of thisspecification should be considered.

The sequence of processes, described above, can be implemented by theuse of hardware or software, or both. To perform the process sequence byusing software, a program describing the sequence may be installed in adedicated hardware element, or a memory, incorporated in a computer, ormay be installed into a computer that can perform various processes.

The program may be recorded beforehand in, for example, a hard disc or aROM (Read Only Memory) that is a recording medium. Alternatively, theprogram may be temporarily or permanently stored (recorded) in aremovable recording medium such as a flexible disc, a CD-ROM (CompactDisc Read Only Memory), an MO (Magneto Optical) disc, a DVD (DigitalVersatile Disc), a magnetic disc, a semiconductor memory or the like.The removable recording medium may be provided in the form of so-called“package software.”

The program may be installed into the computer, read from such aremovable recording medium as specified above. Otherwise, it may betransferred to the computer from a download site, either by wireless orvia a network such as a LAN (Local Area Network) or the Internet. Thecomputer receives the program thus transferred. The program can beinstalled in the recording medium, e.g., a hard disc, provided in thecomputer.

According to the present invention, various processes can be performednot only sequentially in the order described above, but also in parallelor independently, depending on the performances of the devices thatcarry out them or in accordance with necessity. The system implementingthis invention is a logical assembly of various components. Allcomponents of the system are not necessarily arranged within the samehousing.

The present invention is not limited to the embodiment that has beendescribed with reference to the drawings. It would be obvious to anyoneskilled in the art that various changes and modification can be madewithout departing the scope and spirit represented by the claims setforth at the end of this specification.

Industrial Applicability

As has been described, the present invention relates to a wirelesscommunication network that comprises a master that performs acommunication control process and one or more slave that can communicatevia the master. Each slave transmits its various data-processingabilities, in the form of various performance parameters, to the master.The master selects one of the slaves as a candidate for the next master,on the basis of the performance parameters transmitted from the slaves.The master gives each slave the backup-master information that containsthe address and synchronization information, both concerning the slaveselected. From the backup-master information, each slave can determinewhich slave is the next master and can be immediately connected to thenext master when the master is removed from the network. Hence, the userof the master need not select a slave as next master. In addition, theinterruption of communication between the slaves can be shortened, andthe slaves can be connected to the new master quickly and efficiently.

In accordance with this invention, performance parameters are thedata-processing performance items evaluated of each slave, such as theremaining battery power, CPU performance, memory resource and RSSI(electric-field intensity). On the basis of these information items, themaster can select a slave as backup master, which can cope with theoperating condition of the network.

According to this invention, the backup-master information the mastersends to the slaves contains the synchronization information about thebackup master. Therefore, at least a part of the process of establishingsynchronization necessary for the reconstruction of the network need notbe carried out. This makes it possible to reconstruct the networkefficiently within a short time.

In the present invention, backup-master information that is a listshowing devices in the descending order of their master aptitudes may betransmitted to the slaves. Then, the slaves can have information about aplurality of backup masters. Namely, each slave can acquire theinformation of the other devices that constitute the piconet. Thus, ifany slave cannot be connected to the backup master having the highestmaster aptitude when the master is removed from the piconet, because thebackup master has been already removed from the piconet, it may beconnected to the backup mater that has the second highest masteraptitude.

According to this invention, a slave list may be transmitted the backupmaster. Then, in accordance with the slave list the device selected asnew master can be connected to the slaves, one after another, after themaster is disconnected from the slaves. Each slave need not perform anyprocess to connect itself to the master. The device selected as newmaster can use the Bluetooth-device addresses (BD ADDRs) contained inthe slave list and also the synchronization information, all transmittedfrom the previous master. The new master can therefore efficientlyestablish connection with the slaves. In the piconet thus set anew, theslaves can communicate with one another through the new master.

1. A communication processing device configured to function as a master in a wireless communication network which comprises a plurality of slaves which communicate through the master and in which each of the plurality of slaves sends an inquiry to acquire address and synchronization information of the master upon setting up the wireless communication network and receives a signal containing the address and synchronization information of the master and each of the plurality of slaves performs a page process by transmitting a page signal containing attribute information, wherein the master and each of the plurality of slaves are synchronized in terms of frequency axis and time axis, the communication processing device comprising: data-receiving means for receiving data from each of the plurality of slaves wherein each of the plurality of slaves is a device constituting the wireless communication network, wherein capabilities of data processing for items of evaluation are set as performance parameters in the data; a processor which performs a process of determining a master aptitude for each of the plurality of slaves based on the performance parameters received from each of the plurality of slaves, a process of ranking each of the plurality of slaves from highest to lowest based on the determined master aptitude, and a process of determining one of the plurality of slaves, which has a master aptitude with the highest ranking, as a candidate slave set to be a backup-master for next master; and data-transmitting means for transmitting backup-master information to each of the plurality of slaves including address information and synchronization information of the backup-master, said synchronization information of the backup-master relating to comprising at least clock information, wherein the at least clock information allows another plurality of slaves to synchronize with the backup master, the address information of the backup-master is determined by the processor, wherein the another plurality of slaves are a set of slaves among the plurality of slaves without the candidate slave, wherein the another plurality of slaves can establish synchronization of a next network by using the backup-master information transmitted from the data-transmitting means, without each of the another plurality of slaves transmitting another inquiry signal to acquire the address of the backup-master and synchronization information of the backup-master, wherein the performance parameters include at least one of data items of remaining battery power, CPU (computer processing unit) performance, memory resource and RSSI (Radio Signal Strength Indicator), i.e., electric-field intensity, all pertaining to each of the plurality slaves, the processor determines the master aptitude by performing an operation in which a weight coefficient is applied to at least one of the performance parameters, and the master performs a process of transmitting a backup-master activation request packet to the backup master, the backup-master activation request packet requesting for activation of the backup-master.
 2. The communication processing device according to claim 1, wherein the performance parameters include a data item; wherein the data item indicates whether the plurality of slaves can be set only as a network access point (NAP), only as a master of a group ad-hoc network (GN), or as either a NAP or a GN; and the processor only performs the process of determining the master aptitude for slaves among the plurality of slaves that has the data item with indication of GN.
 3. The communication processing device according to claim 1, wherein the wireless communication network is a wireless communication network that performs Bluetooth communication; and the data-receiving means performs a process of receiving packets, each being a BNEP packet generated in accordance with Bluetooth network encapsulation protocol (BNEP) and containing the performance parameters.
 4. The communication processing device according to claim 1, wherein the wireless communication network is a wireless communication network that performs Bluetooth communication; and the data-transmitting means performs a process of transmitting packets, including a BNEP packet generated in accordance with Bluetooth network encapsulation protocol (BNEP) and containing the backup-master information.
 5. The communication processing device according to claim 1, wherein the performance parameters are stored in a BNEP packet generated in accordance with Bluetooth network encapsulation protocol (BNEP); and the processor performs a process of acquiring the performance parameters from the BNEP packets.
 6. The communication processing device according to claim 1, wherein the processor performs a process of storing the backup-master information in a BNEP packet generated in accordance with Bluetooth network encapsulation protocol (BNEP), the backup-master information including address information of the backup-master and synchronization information.
 7. The communication processing device according to claim 1, wherein the processor further generates the backup-master activation request packet that requests for activation of the backup-master.
 8. The communication processing device according to claim 7, wherein the processor performs a process of storing type information (Target UUID (Universal Unique Identifier)) in the backup-master activation request packet, the type information showing whether the backup-master should be set as a NAP (Network Access Point) or a GN (Group Ad-hoc Network).
 9. The communication processing device according to claim 1, wherein the processor figures out master aptitudes for each of the plurality of slaves, based on the performance parameters received from each of the plurality of slaves, and generates a packet containing a list that contains the address information items of each of the plurality of slaves and synchronization information of each of the plurality of slaves based on the master aptitudes, the list showing the address information items in the order of the master aptitudes of respective slaves; and the data-transmitting means performs a process of transmitting the packet containing the list, to the plurality of slaves constituting the wireless communication network.
 10. The communication processing device according to claim 1, wherein the processor further generates a packet to be transmitted to the backup-master, the packet containing a list that contains address information of the plurality of slaves that are devices constituting the wireless communication network and synchronization information of the plurality of slaves; and the data-transmitting means performs a process of transmitting the packet containing the list, to the backup-master.
 11. A communication processing system in a wireless communication network that comprises a master which performs a communication control process and a plurality of slaves which communicate through the master, wherein each of the plurality of slaves sends an inquiry to acquire an address and synchronization information of the master upon setting up the wireless communication network, the communication processing system comprising: the master, being a communication processing device, wherein the master sets a candidate slave to be a backup-master for next master based on data received from each of the plurality of slaves, wherein the received data containing performance parameters that are data-processing performance items evaluated of each of the plurality of slaves, and the master supplies backup-master information including address information and synchronization information of the backup-master to each of the plurality of slaves, said synchronization information of the backup-master comprising at least clock information, wherein the at least clock information allows each of another plurality of slaves to connect to the backup master; and the plurality of slaves being communication processing devices which perform a process of determining data-processing performance items evaluated for the plurality of slaves in a form of performance parameters and transmitting the data-processing performance items to the master, and each of the plurality of slaves perform a process of receiving the backup-master information from the master and storing the backup-master information in memory means, wherein the another plurality of slaves determine the backup-master on the basis of the backup-master information after becoming disconnected from the master, and each of the another plurality of slaves perform a connection process without transmitting another inquiry signal to acquire the address information and the synchronization information of the backup master, wherein the another plurality of slaves are set of slaves among the plurality of slaves without the candidate slave, the performance parameters include at least one of data items of remaining battery power, CPU (computer processing unit) performance, memory resource and RSSI (Radio Signal Strength Indicator), i.e., electric-field intensity, all pertaining to each of the plurality of slaves, a processor of the master determines a master aptitude of each of the plurality of slaves by performing an operation in which a weight coefficient is applied to at least one of the performance parameters, wherein the processor of the master performs a process of ranking each of the plurality of slaves from highest to lowest based on the determined master aptitude, and determines one of the plurality of slaves, which has a master aptitude with the highest ranking, as the candidate slave set to the backup-master for next master, and the master performs a process of transmitting a backup-master activation request packet to the backup master, the backup-master activation request packet requesting for activation of the backup-master.
 12. The communication processing system according to claim 11, wherein the master performs a process of storing the backup-master information in a BNEP packet generated in accordance with Bluetooth network encapsulation protocol (BNEP) and transmitting the BNEP packet to the slaves, the backup-master information including address information of the backup-master and synchronization information of the backup-master.
 13. The communication processing system according to claim 11, wherein the master performs a process of transmitting a backup-master activation request packet to the backup master, the backup-master activation request packet requesting for activation of the backup-master.
 14. The communication processing system according to claim 11, wherein the master generates a packet containing a list and transmitting the packet to the plurality of slaves, the list containing synchronization information of each of the plurality slaves and showing device-address information items of each of the plurality slaves in the order set in accordance with the master aptitudes of the plurality of slaves.
 15. The communication processing system according to claim 11, wherein the master performs a process of generating a packet containing a list and transmitting the packet to the backup-master, the list containing synchronization information and address information items of the plurality of slaves that are devices constituting the wireless communication network.
 16. A master-controlling method implemented on a communication processing device which is to act as a master in a wireless communication network which comprises a plurality of slaves which communicate through the master and in which each of the plurality of slaves sends an inquiry to acquire an address and synchronization information of the master upon setting up the wireless communication network and receives a signal containing the address of the master and synchronization information and performs a page process by transmitting a page signal containing attribute information of the respective slave, whereby the master and each of the plurality of slaves are synchronized in terms of frequency axis and time axis, the method comprising: a data-receiving step, at the communication processing device, of receiving data from each of the plurality of slaves that are devices constituting the wireless communication network, wherein capabilities of data processing for items of evaluation are set as performance parameters in the data; a data-processing step, at the communication processing device, of performing a process of determining a master aptitude for each of the plurality of slaves based on the performance parameters received from each of the plurality of slaves, a process of ranking each of the plurality of slaves from highest to lowest based on the determined master aptitude, and a process of determining one of the plurality of slaves, which has a master aptitude with the highest ranking, as a candidate slave set to be backup-master for next master; and a data-transmitting step, at the communication processing device, of transmitting backup-master information including address information and synchronization information of the backup-master, said synchronization information of the backup-master comprising at least clock information, wherein the at least clock information allows another plurality of slaves in the wireless communication network to connect to the backup master, the address information of the backup-master determined in the data-processing step, and wherein the another plurality of slaves can establish synchronization of a next network by using the backup-master information transmitted from the data-transmitting means, without each of the another plurality of slaves transmitting another inquiry signal to acquire the address of the backup-master and synchronization information of the backup-master, wherein the another plurality of slaves are set of slaves among the plurality of slaves without the candidate slave, the performance parameters include at least one of data items of remaining battery power, CPU (computer processing unit) performance, memory resource and RSSI (Radio Signal Strength Indicator), i.e., electric-field intensity, all pertaining to each of the plurality of slaves, the data processing step includes determining the master aptitude by performing an operation in which a weight coefficient is applied to at least one of the performance parameters, and the data-transmitting step further includes a process of transmitting a backup-master activation request packet to the backup master, the backup-master activation request packet requesting for activation of the backup-master.
 17. The master-controlling method according to claim 16, wherein the performance parameters include at least one of data items of remaining battery power, CPU performance, memory resource and RSSI, i.e., electric-field intensity, pertaining to a slave; and the data-processing step determines the master aptitude based on at least one of the performance parameters.
 18. A non-transitory computer-readable recording medium for storing therein a computer program for executing a method on a communication processing apparatus which is to function as a master in a wireless communication network that comprises a plurality of slaves which communicate through the master and each of the plurality of slaves sends an inquiry to acquire an address and synchronization information of the master upon setting up the wireless communication network and each of the plurality of slaves receives a signal containing the address and the synchronization information of the master and each of the plurality of slaves performs a page process by transmitting a page signal containing attribute information, wherein the master and each of the plurality of slaves are synchronized in terms of frequency axis and time axis, the method comprising: a data-receiving step of receiving data from the plurality of slaves that are devices constituting the wireless communication network, wherein capabilities of data processing for items of evaluation are set as performance parameters in the data; a data-processing step of performing a process of determining a master aptitude of each of the plurality of slaves based on the performance parameters received from the plurality of slaves, a process of ranking each of the plurality of slaves from highest to lowest based on the determined master aptitude, and a process of determining one of the plurality of slaves, which has a master aptitude with the highest ranking, as a candidate slave set to be a backup-master for next master; and a data-transmitting step of transmitting backup-master information including address information and synchronization information of the backup-master, said synchronization information of the backup-master comprising at least clock information, wherein the at least clock information allows another plurality of slaves in the wireless communication network to connect to the backup master, the address information of the backup-master is determined in the data-processing step, and wherein the another plurality of slaves are set of slaves among the plurality of slaves without the candidate slave, wherein each of the another plurality of slaves can establish synchronization of a next network by using the backup-master information transmitted in the data-transmitting step, without each of the another plurality of slaves transmitting another inquiry signal to acquire the address of the backup-master and synchronization information of the backup-master, the performance parameters include at least one of data items of remaining battery power, CPU (computer processing unit) performance, memory resource and RSSI (Radio Signal Strength Indicator), i.e., electric-field intensity, all pertaining to each of the plurality of slaves, the data-processing step includes determining the master aptitude by performing an operation in which a weight coefficient is applied to at least one of the performance parameters, and the data-transmitting step further includes a process of transmitting a backup-master activation request packet to the backup master, the backup-master activation request packet requesting for activation of the backup-master.
 19. A communication processing device being a master in a wireless communication network in which the wireless communication network further comprises a plurality of slaves which communicate through the master and each of the plurality of slaves sends an inquiry to acquire an address and synchronization information of the master upon setting up the wireless communication network and receives a signal containing the address and synchronization information of the master and each of the plurality of slaves performs a page process by transmitting a page signal containing attribute information, wherein the master and each of the plurality of slaves are synchronized in terms of frequency axis and time axis, the communication processing device comprising: a data-receiving unit provided to receive data from each of the plurality of slaves that are devices constituting the wireless communication network, wherein capabilities of data processing for items of evaluation are set as performance parameters in the data; a hardware processor provided to perform a process of determining a master aptitude of each of the plurality of slaves based on the performance parameters received from each of the plurality of slaves, the hardware processor ranks each of the plurality of slaves from highest to lowest based on the determined master aptitude, and provides a process of determining one of the plurality of slaves as a candidate slave set to be a backup-master for next master based on the determined master aptitude with the highest ranking; and a data-transmitting unit provided to transmit backup-master information including address information and synchronization information of the backup-master, said synchronization information of the backup-master comprising at least clock information, wherein the at least clock information allows another plurality of slaves in the wireless communication network to connect to the backup master, the address information of the backup-master is determined by the processor, wherein the another plurality of slaves are a set of slaves among the plurality of slaves without the back-up master, wherein each of the another plurality of slaves can establish synchronization of a next network by using the backup-master information transmitted from the data-transmitting unit, without each of the another plurality of slaves transmitting another inquiry signal to acquire an address of the backup-master and synchronization information of the backup-master, the performance parameters include at least one of data items of remaining battery power, CPU (computer processing unit) performance, memory resource and RSSI (Radio Signal Strength Indicator), i.e., electric-field intensity, all pertaining to each of the plurality of slaves, the hardware processor determines the master aptitude by performing an operation in which a weight coefficient is applied to at least one of the performance parameters, and the master performs a process of transmitting a backup-master activation request packet to the backup master, the backup-master activation request packet requesting for activation of the backup-master. 